This invention relates generally to pressure regulators, and more particularly to pressure regulators for use in underwater breathing apparatus.
Within the past several decades, the sport of skin-diving has enjoyed considerable popularity, so that today there exists an entire industry for supplying equipment for this sport. This industry manufactures and sells a wide variety of instruments, devices and equipment to enable a person to properly breathe underwater so as to enable him to retain beneath the surface for extended periods of time.
One of the most vital concerns in the manufacture of underwater breathing apparatus is the need for a source of air at substantially constant pressure. That is, in order to enable a person to breathe properly and hence function as desired, it is necessary to have a source of air the pressure of which does not fluctuate haphazardly or at random.
In this regard, pressure regulators have been developed which employ a floating pressure sensing device and associated valve stem and valve member movable therewith for controlling the flow of breathing air from a variable pressure source past the valve member. For example, it is known to apply the desired pressure output from the regulator to a floating piston in a manner so that an associated valve tends to close off a pressure source. Within this framework, biasing means have been applied to the floating piston to counteract the pressure applied thereto so that the associated valve member tends to open and increase the pressure supply. In this manner, with a biasing means operable to afford a substantially constant force throughout the range of travel of a piston, a substantially constant output pressure can be maintained. Furthermore it is common to provide an opening in the regulator housing surrounding the biasing means so that changing ambient pressure can be transmitted to the biasing means, thus increasing the regulated pressure as ambient pressure increases and conversely, reducing the regulated pressure as ambient pressure decreases.
Within the above structural context, a distinct and potentially dangerous problem has been encountered by scuba divers in very cold water. Necessarily, ambient water flows into a regulator housing through the above relief openings so as to immerse the biasing means; and should such water be cold enough, it is possible for icing to develop which would inhibit the proper functioning of the biasing means, which in turn could lead to malfunctioning of the entire regulator. It would also be possible for solid contaminants, sand, etc. to enter the regulator housing, thus greatly reducing regulator useful life.